#include<iostream>
      #include<cstdio>
   
      using namespace std;
      unsigned long int array[673366];
      int main()
   
      {
   
   
          array[0]=0;
   
          array[1]=0;
   
          unsigned long int iter=2,n=2,number,end=3,count,sz=3;
  
          scanf("%d",&number);
  
          array[2]=3;
  
          if(number<=2)
  
              printf("%d",number);
  
          else if(number==3)
  
                      printf("2");
  
          else
  
          {
  
              while(number>end)
  
             {

                             n++;

                  if(array[iter]==n)

                  {
  
                      count=iter;
  
                      iter++;
  
                  }
  
                  else if(array[iter]>n)
  
                              count=iter;
  
                  end+=count;
  
                  array[sz++]=end;
  
              }
  
            printf("%d",n);
  
          }   
      }